In the field of telecommunication devices there is a tendency to integrate electrical circuits into entities containing as many functions as possible. Through integration it has been possible to reduce or completely eliminate the need for manual installation of discrete components. This means lower manufacturing costs for products. Because of integration, sizes of wireless cellular terminals have been reduced from kilograms down to a few dozen grams at best. However, integration involves some new problems. Testing of large electrical circuit entities becomes complex and difficult to implement. This may increase a product's manufacturing costs.
One target for integration has been the wireless terminal's radio-frequency part, or RF unit, and the antenna arrangement accompanying it. The RF unit proper and the antenna connected therewith used to be two physically separate components, fabricated as discrete elements. They were mechanically and electrically interconnected in the final assembly of the terminal. Thus it was easy to test them both separately. Now these once-discrete components may constitute a single electrical entity fabricated on/connected to one printed circuit board, connected to the other parts of the terminal during the manufacturing process. In such a solution, also the antenna used by the terminal is, prior to the final assembly, fabricated on/connected to the printed circuit board which serves as a base for the RF unit. However, this solution, which as such is advantageous from the cost standpoint, results in that it is difficult to test the RF unit alone, because the antenna, which now is in constant electrical contact therewith, always affects the measurement results obtained.
One possible solution for the aforementioned problem is to connect to the PCB a special measurement connector between the RF unit proper and the antenna circuit.
One possible solution for the aforementioned problem is to connect to the PCB a special measurement connector between the RF unit proper and the antenna circuit. This measurement connector provides a direct connection to the RF unit output so that the antenna will not affect the measurement results. This way, the operation of the RF unit can be tested direct at the output thereof. If the RF unit is not operating as it should, it can be repaired right away, if possible, and the test can be then repeated. This solution, however, is not cost-efficient as the special measurement connector is expensive and requires installation work. Moreover, reliability problems are known to be associated with the measurement connectors used.
Operation of the RF unit may naturally be tested together with the antenna arrangement attached to it. In that case the measuring instrument must be connected in parallel with the antenna of the terminal, using electromagnetic coupling of some sort. It is known that antenna operation is affected by all components, especially those containing metals, in its vicinity. Therefore, in this measuring arrangement the terminal has to be assembled, at least for those components that are regarded as affecting the radiation characteristics of the antenna. If testing indicates erroneous operation of the RF unit, the already-installed other mechanical parts/components of the terminal have to be removed before actual repair can be done. After the repair, the terminal must again be assembled for re-testing. Such a procedure takes time and increases testing costs.